An early cyclone method and apparatus is known from U.S. Pat. No 453,105 (Bretney), issued May 26, 1891, in which there are two stages, in line, in the separating cyclone. A frequent problem with this and later cyclone devices is that efficiency of separation is markedly decreased after either capacity of feed solids concentration are increased. Later cyclone designs eliminated the small in-line second stage cyclone, but introduced only slight construction changes, not changing, however, the general principle of cyclone operation and not eliminating these disadvantages.
It is therefore one object of the present invention to provide a method and apparatus to separate particulate fluid suspension or liquid mixtures with high and stable efficiency for a wide range of feed capacity and feed solids concentration.
A further object of the present invention is to reduce the number of growing underflow apexes, which have to be used for an increased capacity or feed solids concentration to avoid a decreasing of given cyclone's separation efficiency.
Still another object of the present invention is to reduce the number of cyclone sizes, because the range of the capacity with the high separation efficiency is wider for given unit.